1. Field of the Invention
The present invention relates to a method and apparatus that allows in-circuit logic emulation, hardware modeling, simulation acceleration and direct industrial process control from schematic designs. The in-circuit logic emulation allows computer-based schematic designs to directly affect the behavior of external electronic hardware and electro-mechanical devices. Hardware modeling is embedding external hardware devices in computer-based schematic designs and directly affecting their behavior. The simulation acceleration uses actual hardware in place of complex simulated circuits. The industrial process control is similar to the in-circuit emulation, except that the computer-based designs directly control industrial equipment. The invention discloses a unified design environment that allows for direct functional interaction of computer-based designs with electrical hardware.
2. Prior Art
Since testing of a new product design can be very involved, to speed the process, designers are converting their schematics into intermediate hardware that is easy to program and test in conjunction with the target hardware for which the design has been made. Only when the intermediate hardware design has been proven, the design is then produced. A prime example of this approach are products from Quickturn Systems Inc. which allow the designer to convert a schematic design into multiple Xilinx field programmable gate arrays (FPGAs), which can be effectively tested in conjunction with a target hardware. However, such intermediate hardware-based design emulators are very expensive and few can afford it. The programming of such design emulators is cumbersome and takes a significant amount of time. Furthermore, connecting the hardware-based emulators to the target hardware is both error-prone and time consuming.
Another major shortcoming of present design emulators is that their timing may substantially differ from the timing of the design, thus creating wrong test conditions.
Still another problem is that the FPGA devices have unpredictable internal delays and sometimes fail to operate as required by the design. Additional effort is then required to verify that the original schematic design has been properly converted by the emulator.
Since some integrated circuit (IC) models would be too slow to execute, the actual parts are used in place of the IC model. The equipment for feeding output signals from the actual IC devices in place of their models is called "hardware modeling equipment". Many examples of such hardware modeling equipment have been proposed and some have been built.
For example, the method and apparatus disclosed in the U.S. Pat. No. 4,744,084 of Beck, et. al., allow for hardware modeling of ICs of great complexity and speed. However, this patent suffers from the same shortcomings as other similar equipments which attempt to mimic the actual operational environment of the IC device and provide precise timing simulation of the device. As a result, the equipment is burdened with sophisticated clocking circuits for exercising IC devices, and with time shifters to vary the IC output signals within some predetermined range.
The high speed operation of the hardware modelers is achieved by using batch processing. However, this makes the equipment even more costly and thus, less affordable to designers. There are also some other cumbersome restrictions which further complicate the design of the hardware modelers. None of the above restrictions exist in the present invention which is based on a real-time interactive simulator, making the hardware modeling equipment simple and low in cost.
The controllers for industrial applications are highly customized and thus cannot offer the economy of scale. Also, the programming of such controller is often carried out by using specialized computer languages which are expensive, time consuming and difficult to maintain.
The present invention allows for implementation of such industrial controllers by means of computer-based schematic designs. No specialized hardware needs to be built and since the schematic designs can be described with the VHDL hardware description language, therefore the industrial controllers are simple and straightforward.
Since the present art requires a great variety of hardware to be built for various applications, a need exists for a universal, low cost, computer-driven tool and method that would substitute for all this highly specialized hardware. Specifically, a need exists for lower cost and improved design in-circuit emulators, simulation accelerators, hardware modeling equipment and industrial controllers that would minimize these and other problems in the prior art.